1. Field of the Invention
This invention relates to an improvement for fluorescent lamps capable of enlarging its useful life by incorporating a plurality of hermetically sealed enclosures acting as independent lamps.
2. Description of the Prior Art
In preparing fluorescent lamp tubes, it is the practice to coat the filament of the electrodes with a suspension of strontium and barium carbonates and zirconia or powdered zirconium in which suspension the coils are dipped and when the coils are heated to activate them in service, the carbonates are decomposed to form a coating consisting of a mixture of barium and strontium oxides, or a mixture of barium and strontium oxides and zirconia or zirconium. There is also enclosed in the tubes a small amount of mercury and as inert gas, such as argon, krypton, or a mixture of argon and krypton, and when an electric current is passed between the electrodes, ultra-violet radiations are produced which are transformed by the fluorescent material into visible light.
The complete failure of gas-filled tubes, unless defects are present in their mechanical parts, is generally due to the sputtering off of all of the coating upon the filaments of the electrodes. However, it is well known that gas-filled tubes of the fluorescent type gradually blacken in service even when the coating of the oxides upon the filaments is still intact. The blackening of the tubes is particularly pronounced at the end portions of the tubes in proximity to the electrodes although more or less blackening of the tubes occurs throughout the entire length of the tubes. This blackening is caused by a film comprising mercury which is deposited upon the interior surface of the tube during service which the mercury may be entrained with or combined with other elements or compounds on the interior surface of the tube.
Several attempts have been made in the past to recondition gas filled lamps, and more particularly, fluorescent lamps. One of these attempts is described and claimed by Louis C. Stringer in U.S. Pat. No. 2,304,714. However, even though the gas inside the lamp is changed like in the present invention, it is done by breaking the glass tube and fusing the edges together afterwards. This method is costly, time consuming and impractical.
Another method and apparatus of interest is described in U.S. Pat. No. 2,884,298 issued to Thomas T. Bryen. This method and apparatus involves the use of heat to get rid of the blackening of the tubes. Again, this method and apparatus is very cumbersome and impractical.
Still another approach is described in U.S. Pat. No. 2,733,973 issued to Wallace Shaffer. Here, a high voltage is applied, between 5,000 and 12,000 volts, with a load current between 1 and 12 milliamperes, in order to "rejuvenate" the lamp tube. This invention requires the use of a high voltage generator and its operation may be quite dangerous. Furthermore, it is not effective in all cases as the inventor himself admits in said patent specification that it is not known with certainty what transpires in the tubes when a high voltage is applied to it.
None of these patents, however, provide for an easy solution to the user. Most of the prior art requires the use of complicated rejuvenating equipment. The user, on the other hand, wants a fast solution and it is that what the present invention gives him. The user can easily rotate the end cap on each end of the tube and the problem is fixed.
Other related inventions have been studied as part of the prior art. None of these inventions anticipate the novel features of the present invention.